Switch structure



Feb. 13, B, E SHAW 2,190,338

SWITCH STRUCTURE Filed Jan. 3, 1939 Patented Feb. 13, 1940 UNITED STATES SWITCH STRUCTURE Burton E. Shaw, Bristol, Ind., assignor to Penn Electric Switch Co., Goshen, Ind., a corporation of Iowa Application January 3, 1939, Serial No. 248,973

ll Claims.

.an object oi my present invention is to provide a switch structure including control means efiective to adjust the range of the switch and in one position to positively move the switch to open circuit position.

Another vobject is to provide manual control means for a switch such as one responsive to pressure or the like, the manual control in a plurality oi positions effecting a change in the range of operation of the switch and in one predetermined position positively opening the switch so that it no longer operates automatically until such time as the control knob of the manual control mechanism returned to a range adjusting position.

@ther objects, purposes and characteristic features ci' my switch structure will be in part olevious from the accompanying drawing and in part pointed out in the following description or the invention as it progresses. In describing the invention in detail reference will be made to the accompanying drawing in which reference characters designate corresponding parts throughout the several views thereof, and in which:

Figure l is a iront elevation of a switch strueture embodying my invention with the cover plate omitted from the casing;

Figure 2 is a plan view of the switch structure showing the manual control knob for eectlng range adjustment and positive opening of the switch in full and dotted lines respectively;

Figure 3 is a vertical sectional view of my switch structure as taken on the line 3-3 of Figure l;

Figure 4 is an enlarged sectional view on the line 4-4 of Figure 3 showing the coaction of a pair of projections with each other for eiecting positive opening of the switch; and

Figure 5 is an enlarged sectional view on the line 5-5 of Figure 1 showing details of the control knob of my switch structure.

On the accompanying drawing I have used the reference numeral I0 to indicate generally a switch casing and I2 a cover therefor. Within the switch casing I0 a supporting bar I3 preferably of insulation is provided. Stationary contacts I4 and I5 are supported thereby adjacent a permanent magnet I6.

A bracket is mounted on the bar |3 and carries a pivot pin I8. A switch arm I9 is pivoted thereto and carries contacts and 2| for coaction with contacts I4 and I5 respectively. 'I'he contact 2| is carried by a leaf spring 22 and extends loosely through an opening in the switch arm I 9. The switch arm I9 constitutes an armature for the magnet I6 to secure snap action of the switch structure in a. well-known manner.

In the switch casing I0 I provide a bracket 22 carrying a pivot pin 23. A bell crank arm 24 ls pivotally mounted thereon and operatively con- (fUl. 20G-83) nected with the switch arm |9 by means of a leaf spring 25 and a link 2li-2l.

A bellows housing 28 is mounted on the switch housing I0 and houses a bellows 29. The bellows it has an operating pin 29a connected with its head while the base of the bellows is sealed relative to the housing 29. A capillary tube 30 extends from the housing 28 to a capillary bulb Si which is charged with a suitable liquid for producing pressure changes in the housing 28 in response to temperature changes affecting the bulb 3|.

A range adjusting spring 32 is provided for the switch structure and has its lower end connected with the bell crank arm 3e. Its upper end is threaded on a plug 33 into which an adjusting shaft 34 is screw threaded. The shaft 3i extends rotatably through an opening 35 in the top of the switch casing l0 and terminates in an enlarged head 36 which provides a shoulder engaging the upper surface of the switch casing.

Mounted on the head 36 is a control knob 3l secured thereto at any desired radial position by a set screw 38. The knob 3l has a peripheral groove 39 in the bottom thereof and a stop pin 40 is carried by the knob and projects into this groove. A stationary stop pin 4| is carried by the switch casing I9 and is located in the path of rotational movement of the shown in Figure 5.

The upper end of the head 36 is slotted so that the shaft 34 may be rotated at the factoryvfor initial adjustment of the spring 32, after which the knob 31 is secured in position.

Mounted on the shaft 34 ls a cam disc 42 secured in the proper radial position thereon to correspond to the knob 31 by a set screw 43. The disc 42 carries a projection in the form of a rivet head 44 arranged parallel to the axis out of the shaft 34.

A second projection 45 preferably in the form of a, plate of insulating material extends from the switch arm I9 and the plate 45 has an inclined edge 46 adapted at times to coact with the rivet head projection 44.

stop pin 40 as Practical operation In the operation of my switch structure, with the projection 44 normally out of registry with the projection 45, the switch contacts controlled by the switch arms I9 move to open and closed circuit positions alternately as a result of reduction and increase respectively in the temperature affecting the bulb 3|. By way of illustration, the contacts may be included in the circuit of a refrigerant compressor motor and the bulb 3| may be responsive to temperature changes as a vresult of alternate operation and non-operation of the refrigerant compressor motor.

A refrigerant compressor motor control switch of the character disclosed is particularly adaptable for beer coolers and the like where it is desirable to have some range of adjustment under selective control of the operator. For this purpose the knob` 31 is provided so that temperatures for instance anywhere between 32l and 39 degrees .minimum may be secured depending on whether the knob 31 is rotated to the left to a position indicated by a projection 41 on a scale plate 48 or rotated toward the right as far as it will go until the stop pin 40 strikes the stop pin 4l on its upper side as viewed in Figure 5. Intermediate temperatures can be secured by adjusting the pointer 49 of the knob to intermediate positions as desired.

There are certain times when it is desirable to have a beer cooler not operating and instead of providing a main line switch in series with the control switch I provide for this in the one switch disclosed by making the parts operable to positively open the switch even though the bellows 29 is in position calling for a cold circuit condition thereof by rotating the knob 31 counter-clockwise until its pointer 49 registers with a projection 50 of the scale plate 48. This position is shown by dotted lines in Figure 4.

It will be noted that the lobelike projection 44 has moved to a position engaging the inclined surface 46 and then further to a position under the extension 45 which results in raising the projection 45 and moving the switch arm I9 to open circuit position as shown by the dotted lines in Figure l. The switch arm can be moved to this position irrespective of the position of the bellows 29 and to permit greater ease of such movement and consequent expansion of the vapor in the housing 28 surrounding the bellows 29 I provide the resilient connection consisting of a leaf spring 25. As shown by the dotted lines in Figure 1 this connection merely springs upwardly when the switch arm is positively opened though the bell crank 24 remains in lowered position.

Having described one specific embodiment of my switch structure and the operation thereof I desire it to be understood that this form is selected to facilitate the disclosure of the invention rather than to limit the number of forms which it may assume. It is to be understood further that various modifications, adaptations and alterations may be applied to the specific form of the invention disclosed to meet the requirements of practice without in any manner departing from the spirit and scope of the present invention except as set forth in the claims appended hereto.

I claim as my invention:

1. In a switch structure of the character disclosed, a switch arm, condition responsive means, a lever operated thereby, means for operatively connecting said lever to said switch arm whereby the condition responsive means normally moves the switch arm through a path of movement effective to make and break an electric circuit controlled by said switch arm, a range adjusting spring for said lever, an adjusting shaft for said range adjusting spring and operable upon rotation to effect variation in the tension thereof on said lever, a projection on said shaft coacting with saidswitch arm to move it to open circuit position when the adjusting shaft assumes a predetermined position, said operative connection including a leaf spring having one end anchored to said lever and-its other end connected with said switch arm to permit such movement of the able upon rotation to effect variation in the tension thereof, said shaft being arranged adjacent said switch arm and at right angles thereto, a I

projection from said switch arm terminating adjacent said shaft, a second projection carried by said shaft and extending axially thereof, said second-projection being lobelike and operable to engage the projection from said switch arm when the shaft is in one position of its rotation and force the switch arm to open circuit position against the constraint of said condition responsive means to retain it in closed circuit position, said rst projection having an inclined face for said second projection to engage to effect such forcing of the switch arm to open circuit position.

3. In a switch structure of the character disclosed, a movable circuit controlling member, condition responsive means `operatively connected therewith to normally move the member through a path of movement effective to make and break an electric circuit controlled thereby, a range adjusting spring for said condition responsive means, an adjusting shaft for said range adjusting spring and operable "upon rotation to effect variation in the tension thereof, said shaft being arranged adjacent said circuit controlling member, a projection from said member terminating adjacent said shaft, a second projection carried by said shaft and extending axially thereof, said second projection being lobelike and operable upon the shaft assuming a predetermined position of its rotation to engage 'the projection from said member to force it in a direction axially of said shafty to open circuit position against the constraint of said condition responsive means to retain it in closed circuit position.

4. In a switch structure of the character disclosed, a casing, a switch arm pivoted therein, condition responsive means, means for operatively connecting said condition responsive means to said switch arm whereby vthe condition responsive means normally moves the switch arm to its different circuit controlling positions, a range adjusting spring for said condition responsive means, an adjusting shaft for said range adjusting spring and operable upon rotation to effect variation in the effect thereof, said shaft being arranged adjacent said switch arm, Ia projection from said switch arm terminating adjacent said shaft, a second projection carried by said shaft and operable to engage the projection from said switch arm and force the switch arm in a direction axially of said shaft to open circuit position against the constraint-of saidA condition responsive means to retain it in closed circuit position, said shaft being slotted for factoryadjustment, a control knobthereon and means to secure said control knob in a desired position of rotation relative thereto.

'BURTON E. SHAW. 

